I just noticed last night that when my wife comes to a stop in her MKT, the heat on the passenger side quickly goes cold. It felt about like outside air. As soon as the engine speeds up, the air from the vents would go hot again. I mentioned this to her while sitting at a stop light and she said her (driver's) side was not doing this. The kids also didn't complain about getting cold at stops, so I'm guessing this is isolated to the passenger side front. Hmmm.....
-Rod